I'll jump in fairly late to the chat, and add my own perspective.
On the other hand. Small scale? You're a ****ing monster. You go into a WSG, with a single healer, you'll be nearly unstoppable. Pop your defensives, charge in, and take care of the other team. You can put out INSANE amounts of damage. We're talking 10-20k crits on a single person.
I have many memories of me popping a single Shockwave that would crit between 7.000 and 13.000 on each and every person in front of my character. Sometimes, that would round up 5+ players being not only stunned for 4 full seconds, but also taking off between half and a third of their health in a split second. If this isn't pure pressure, I don't know what is.
Protection warrior is VERY viable in both large scale AND small scale PvP, but with two different purposes. One for the damage, the other for the massive CCs. You have a 4 second AOE stun that has a 17 second cooldown and a single target stun that lasts for 5 full seconds, with only 30 seconds cooldown.
You have some of the strongest defensive cooldowns in the game and some of the best offense that is obtainable.